Investigate choco solver

[bjornregnell]

The Choco solver has a liberal license:

• https://choco-solver.org/
• https://github.com/chocoteam/choco-solver

Investigate if it can be offered as an alternative reqt solver back-end to jacop.

Comparisons:

• https://www.se.cs.uni-saarland.de/theses/MartinBauerMA.pdf

• https://java.libhunt.com/compare-jacop-vs-choco-solver